Aluminum alloy as bearing metal



Patented Sept. 17, 1940 UNITED STATES PATENT OFFICE 2,215,445 ALUMINUMALLOY AS BEARING METAL g Eugen Vader-s, Frankfort-on-the-Main, GermanyNo Application February 10, 1940, Se-

rial No. 318,372.

In Germany December, 16,

4 Claims. (01. 75-148) In the white metal bearings heretofore commonlyused the base metal consists principally of tin or of lead. The tingenerally contains additions of antimony, bismuth, copper, etc., where"as the lead is alloyed principally with antimony and bismuth. Thebearing metals having a tin base have up to now been considered the bestof their kind. But in consequence of their high tin content whichamounts up to 90%, they are very expensive so that for the sake ofeconomy the expensive tin has been replaced by the cheaper lead. Thelead content is very often used in the same proportion as the tin in thetin bearing ing metal alloy. provided that other metals exist,

which when added to this base metal alloy, form hard compo ndswithit.Aluminum is known to form numerous compounds with other metals and ithas been proposed to use aluminum alloys for bearing purposes. This has,on several occasions, been tried but with very little successconsidering the fact that most aluminum bearing metals of the typereferred to contain hard compounds which wear the axle too much. Bearingmetals of this kind are, e. g., the aluminum-silibon-alloys with highsilicon content of aluminum-magnesium-silicon-alloys.

According to the present invention much more useful aluminum alloysresult from the addition of metals which form with the aluminum none orat leastonly few hard compounds, thus resulting. in no damage being doneto the axle even after an extended time of working. Such additions areantimony andlead which may be present in quantities up to 10% each. Theantimony forms with aluminum the compound AlSb which is present in thebase. alloys as bearing component. Lead does not combine with aluminum.According to the opinion ofseveral exp'erts it is not soluble at all inthe aluminum. If aluminum be melted together with lead, at the time ofsolidification a separation of the aluo minum andlead takes place, i.e., the lead is as insbluble in the aluminum as oil in water. By

adding antimony to the aluminum this sharp separation of lead from. thealuminum is obviated, so that with the presence of a sufllcient s5quantity of antimony larger quantities of lead are distributed in thealuminum, resulting in an alloy which shows a structure more especiallysuitable for hearing purposes. Apart from aluminum an AlSb compound iscontained in it, while lead is either alloyed with this Al-Sb compound,5 or else is segregated in form of small drops which form an improvement.of the sliding surface, in-

asmuchas in the case of interruption of the .oil-

ing or sudden stoppage of the running or the bearing no damage will becaused to the axle. 10

All tests made in this direction proved in every instance that thesliding surface of the axle was covered with a thin layer'of thealuminum alloy; that could easily be removed. Thealuminum-antimony-lead-alloys have a crystalline structure as also theother qualities of the knownwhite bearing metal. Thus they are easilyformable' even in a cold state. t

The sliding properties have been ascertained with an especially suitablealloy consisting of m 2.5% Pb, 2.5% Sb and the balance aluminum by abearing testing installation. On that occasion specific surfacepressures of about 200 kg./cm.

' could be reached at a speed of 10 m./sec, whereby the bearingtemperature rose up' to'100f C. The test axle that consisted ofnon-hardened steel was.perfectly smooth and free from indents at the endof the test. Apart from the bearing testing machine, tests were made incombustion motors in which the connecting rod bearings con- 110 sistedof the new aluminum alloys. These combustion motors have been driven byan electrical motor, so that the bearings were fullycharged. Also inthat case the bearings of the new alloy proved successful, for during aworking period Per cent Pb 1.

Sb- 1 I 2.5 1A1 J I Balance or Per cent Pb- 1 2.5

A1 Balance In cases in which the price of the bearing metal is of lesserimportance, the tin content may also be higher. An alloy having a highertin content is about the following:

Per cent Pb 2.5 Sb 2.3 Sn 5 Al Balance Since tin alloys well eitherwith. antimony or with lead, it is particularly valuable as addition tothe ternary aluminum-lead-antimony-alloy, but also the other metalsadded to, this three-partalloy result in very useful bearing metals.

While the additional metals mentioned above influence chiefly thesliding properties, the further possible additions of at least one ofthe metals of the group consisting of copper, nickel, co-

' balt,iron, manganese and zinc in quantities of 0.1-10% and silicon inquantities of 0.1-3% especially effect a strengthening of the bearingmetal which consequently -is more suitable to resist higher pressures.Especially an addiiton of manganese has proved very effective, inasmuchas it not only, increases the hardness of the alloy, but even improvesessentially the sliding properties. An alloy that proved particularlyuseful for the automobile motor is composed as follows: 2.5% Pb, 2.5%Sb, 3% Mn, remainder Al.

The basic alloy of aluminum with 1 to 10% of lead, 1 to 10% of antimonyand 0.1 to 3% of sili-' con may contain an addition of a metal of thegroup consisting of zinc and cadmiumin quantitles from 0.1 to 10%. 'Thezinc preferably is added in an amoutn of 0.1 to 10% and the cadmium inan amount of 0.1.to 5%.

. Further alloys that correspond about to the properties of the abovementioned alloys are as follows:

Percent The addition of metals of a higher melting point further servethe purpose of making the bearing metals capable of resisting highertemperatures. While it is correct that with most of the additionalmetals named above. the melting point of aluminum is lowered to theeutectic point, the,

substantially all aluminum.

could be reached without a clinging or sticking to the axle havingoccurred. Naturally with such high temperatures the higher heatexpansion of the aluminum alloys has to be taken into account byprovision of a greater bearing-play..

If the new bearing metals are used under favorable condiitons, i. e.,presence of ample quantitles of lubricants, they show but a small wear,even after a comparatively short running-in period.

Summing up, it may be said that with the new bearing metals having analuminum base as compared with the hitherto known bearing metals,

the following advantages exist:

1. Easier running-in,

2. High resistance to wear, a 3. Possibility of using unhardenedaxles,4. High resistance to temperature.

adjusted in sucha way that the segregations remain at a minimum. Thealloys may further be pressed, forged or rolled. In this respect itissurprising that the annealing in the drawing of rods and tubes may beaccomplishedat about 500 C. in spite of the leadand antimony-contentwithout a segregation of the alloys occurring thereby.

For the production of an alloy'as uniform as (possible, firstr of allantimony is melted together with aluminum whereupon lead is added assuch or as a preliminary alloy.

, The rolling possibility moreover makes it possible to roll up thealloys to a firmer sheet base that may consist of iron or copper alloysor also of hardenable aluminum alloys and to produce from the compoundmetal sheets thus obtained especially firm bearing shells.

I claim: a

1. A bearing metal alloy containing about of lead, 1-10% of antimony,0.1-3% of silicon, and 0.1-10% of a member of the group consistingofzinc and cadmium, the balance being substantially all aluminum.

2. A bearing metal alloy containing about silicon, and a member of thegroup consisting of zinc and cadmium, the zinc in an amount of 0.1-10%and t e cadmium in an amount of 0.1-5%, the bal ce being substantiallyall aluminum.

.3; A bearing metal alloy containing about 140% of lead, 110% ofantimony, 0.1-3% of silicon, and 0.1-10% of zinc, the balance beingsubstantiallyall aluminum.

4. A hearing metal alloy containing about I 1-10%- of lead,,l,10% ofantimony, 0.1-3% of silicon, and 0.1-5% of cadmium, th balance beingnouns vsnnas.

